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  Subjects -> ENGINEERING (Total: 1961 journals)
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ENGINEERING (1114 journals)            First | 5 6 7 8 9 10 11 12 | Last

Mathematics of Control, Signals, and Systems (MCSS)     Hybrid Journal   (Followers: 5)
Mauerwerk     Hybrid Journal  
Measurement     Hybrid Journal   (Followers: 1)
Measurement Science Review     Open Access   (Followers: 1)
Meccanica     Hybrid Journal   (Followers: 1)
Mechatronics     Hybrid Journal   (Followers: 4)
Medical and Biological Engineering and Computing     Hybrid Journal   (Followers: 2)
Medical Engineering & Physics     Hybrid Journal   (Followers: 9)
Membrane Science and Technology     Full-text available via subscription   (Followers: 2)
Membrane Technology     Full-text available via subscription   (Followers: 1)
Memetic Computing     Hybrid Journal  
Metal Powder Report     Full-text available via subscription   (Followers: 2)
Metallurgist     Hybrid Journal   (Followers: 2)
Metaphysica     Hybrid Journal   (Followers: 1)
Metascience     Hybrid Journal   (Followers: 1)
Metrologia     Full-text available via subscription   (Followers: 1)
Microelectronic Engineering     Hybrid Journal   (Followers: 4)
Microelectronics International     Hybrid Journal  
Microelectronics Journal     Hybrid Journal   (Followers: 3)
Microelectronics Reliability     Hybrid Journal   (Followers: 6)
Microfluidics and Nanofluidics     Hybrid Journal   (Followers: 9)
Micromachines     Open Access   (Followers: 1)
MNASSA : Monthly Notes of the Astronomical Society of South Africa     Full-text available via subscription   (Followers: 1)
Modelling and Simulation in Engineering     Open Access   (Followers: 4)
Modern Applied Science     Open Access   (Followers: 1)
Molecular BioSystems     Full-text available via subscription   (Followers: 1)
Molecular Engineering     Hybrid Journal  
Molecular Pharmaceutics     Full-text available via subscription   (Followers: 9)
MRS Bulletin     Full-text available via subscription   (Followers: 5)
MRS Online Proceedings     Full-text available via subscription   (Followers: 1)
Multiagent and Grid Systems     Hybrid Journal  
Multidimensional Systems and Signal Processing     Hybrid Journal  
NANO     Hybrid Journal   (Followers: 6)
Nano Letters     Full-text available via subscription   (Followers: 42)
Nano Research     Hybrid Journal   (Followers: 4)
Nano Reviews     Open Access   (Followers: 15)
Nanopages     Full-text available via subscription   (Followers: 1)
Nanoscale and Microscale Thermophysical Engineering     Hybrid Journal   (Followers: 3)
Nanoscale Systems : Mathematical Modeling, Theory and Applications     Open Access  
Nanotechnologies in Russia     Hybrid Journal   (Followers: 1)
Nanotechnology     Hybrid Journal   (Followers: 9)
Nanotechnology Magazine, IEEE     Full-text available via subscription   (Followers: 13)
Nanotechnology Reviews     Full-text available via subscription   (Followers: 4)
Natural Hazards     Hybrid Journal   (Followers: 228)
Nature Nanotechnology     Full-text available via subscription   (Followers: 45)
Naval Engineers Journal     Hybrid Journal   (Followers: 3)
NDT & E International     Hybrid Journal   (Followers: 11)
Nexo Revista Científica     Open Access  
Nigerian Journal of Technological Research     Full-text available via subscription  
Nigerian Journal of Technology     Full-text available via subscription  
NIR news     Full-text available via subscription  
Nonlinear Dynamics     Hybrid Journal   (Followers: 5)
Nonlinear Engineering : Modeling and Application     Full-text available via subscription   (Followers: 1)
Nonlinearity     Full-text available via subscription   (Followers: 2)
Nova Scientia     Open Access  
NTM Zeitschrift für Geschichte der Wissenschaften, Technik und Medizin     Hybrid Journal   (Followers: 4)
Nuclear Engineering and Design     Hybrid Journal   (Followers: 12)
Numerical Algorithms     Hybrid Journal   (Followers: 2)
Numerical Heat Transfer, Part A: Applications: An International Journal of Computation and Methodology     Hybrid Journal   (Followers: 5)
Numerical Heat Transfer, Part B: Fundamentals: An International Journal of Computation and Methodology     Hybrid Journal   (Followers: 7)
Ocean Science Journal     Hybrid Journal   (Followers: 3)
Oil and Gas Journal     Full-text available via subscription   (Followers: 11)
Online Journal for Global Engineering Education     Open Access  
Open Journal of Fluid Dynamics     Open Access   (Followers: 3)
Open Journal of Safety Science and Technology     Open Access   (Followers: 3)
Operations Research Letters     Hybrid Journal   (Followers: 4)
Optical Communications and Networking, IEEE/OSA Journal of     Hybrid Journal   (Followers: 3)
Optimization and Engineering     Hybrid Journal   (Followers: 2)
Opto-Electronics Review     Hybrid Journal   (Followers: 1)
OR Spectrum     Hybrid Journal  
Organic Electronics     Hybrid Journal   (Followers: 3)
Ozone Science & Engineering     Hybrid Journal   (Followers: 1)
Papers In Regional Science     Hybrid Journal   (Followers: 6)
Particle & Particle Systems Characterization     Hybrid Journal  
Particulate Science and Technology: An International Journal     Hybrid Journal   (Followers: 1)
Perspectives on Science     Hybrid Journal   (Followers: 4)
Pesquisa Operacional     Open Access  
Pest Management Science     Hybrid Journal   (Followers: 5)
Petroleum Science     Full-text available via subscription   (Followers: 2)
Phase Transitions: A Multinational Journal     Hybrid Journal  
Philosophical Transactions of the Royal Society A: Mathematical, Physical and Engineering Sciences     Full-text available via subscription   (Followers: 5)
Physica B: Condensed Matter     Hybrid Journal   (Followers: 5)
Physica C: Superconductivity     Hybrid Journal  
Physica D: Nonlinear Phenomena     Hybrid Journal   (Followers: 3)
Physics of Fluids     Hybrid Journal   (Followers: 24)
Planning News     Full-text available via subscription   (Followers: 3)
Plasma Devices and Operations     Hybrid Journal   (Followers: 3)
Plasma Science and Technology     Full-text available via subscription   (Followers: 2)
Plasmonics     Hybrid Journal  
Platinum Metals Review     Open Access   (Followers: 2)
Polar Research     Open Access   (Followers: 1)
Polar Science     Hybrid Journal   (Followers: 3)
Polímeros: Ciência e Tecnologia     Open Access   (Followers: 1)
Polish Maritime Research     Open Access  
Polymer Engineering & Science     Hybrid Journal   (Followers: 13)
Polymer International     Hybrid Journal   (Followers: 2)
Polymer Science Series A     Hybrid Journal   (Followers: 3)
Polymer Science Series B     Hybrid Journal   (Followers: 3)
Polymer Science Series C     Hybrid Journal   (Followers: 4)
Polymer-Plastics Technology and Engineering     Hybrid Journal   (Followers: 4)

  First | 5 6 7 8 9 10 11 12 | Last

Journal Cover Reactive and Functional Polymers
   Journal TOC RSS feeds Export to Zotero [6 followers]  Follow    
   Hybrid Journal Hybrid journal (It can contain Open Access articles)
     ISSN (Print) 1381-5148
     Published by Elsevier Homepage  [2570 journals]   [SJR: 0.834]   [H-I: 55]
  • Thin-film composite membranes for organophilic nanofiltration based on
           photo-cross-linkable polyimide
    • Abstract: Publication date: Available online 8 October 2014
      Source:Reactive and Functional Polymers
      Author(s): Sven Behnke , Mathias Ulbricht
      This work demonstrates that it is possible to prepare new, competitive thin-film composite (TFC) membranes with a polyolefin ultrafiltration membrane as support and with a non-porous photo-cross-linked polyimide as separation layer for organic solvent nanofiltration. The commercial polyimide Lenzing P84® was modified by a polymer-analogous reaction to introduce side groups with carbon-carbon double bonds to increase its photo-reactivity with respect to cross-linking. Polymer characterization revealed that this was successfully achieved at acceptable level of main chain scission. The higher reactivity of the photo-cross-linkable polyimide had been confirmed by comparison with the original polymer; i.e., shorter gelation times upon UV irradiation, higher suppression of swelling by solvents and complete stability in strong solvents for not cross-linked polyimide such as dimethylformamide (DMF) had been obtained. For films from unmodified and modified polyimide, the degree of swelling in various solvents could be adjusted by UV irradiation time. Photo-cross-linking of the original polyimide did not lead to stability in DMF. TFC membranes had been prepared by polymer solution casting on a polyethylene ultrafiltration membrane, UV irradiation of the liquid film and subsequent solvent evaporation. Polyimide barrier film thicknesses between 10 and 1 μm were obtained by variation of cast film thickness. Performance in organic solvent nanofiltration was analyzed by using hexane, toluene, isopropanol and DMF as well as two dyes with molar masses of ∼300 and ∼1000 g/mol. Permeances of TFC membranes from unmodified polyimide were low (<0.1L/hm2bar) while rejections of up to 100% for the dye with ∼1000 g/mol could be achieved. TFC membranes from modified and photo-cross-linked polyimide had adjustable separation performance in DMF with a trade-off between permeance and selectivity, in the same range (e.g.: 0.3 L/hm2bar and 97% rejection for the dye with ∼1000 g/mol) as a commercial conventional polyimide membrane tested in parallel. The established membrane preparation method is promising because by tuning the degree of cross-linking of the polymeric barrier layer, the membrane separation performance could be tailored within the same manufacturing process.


      PubDate: 2014-10-12T07:25:25Z
       
  • Macroporous polymers tailored as supports for large biomolecules: Ionic
           Liquids as porogenic solvents and as surface modifiers
    • Abstract: Publication date: Available online 8 October 2014
      Source:Reactive and Functional Polymers
      Author(s): Diana Flor Izquierdo , Malcolm Yates , Pedro Lozano , M. Isabel Burguete , Eduardo García-Verdugo , S.V. Luis
      Highly ordered rod-like polymeric monoliths with large-pores have been successfully synthesized using ionic liquids (ILs) IL-1 (1-Butyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide [BMIM][NTf2]) and IL-2 (1-octyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide [OMIM][NTf2]) as alternative porogenic solvents. The presence of ILs can not only promote the formation of a highly ordered macroporous structure, control the morphology of the polymer and control the chemical composition of surfaces for monoliths prepared from DVB. In this regard, post-functionalization of the monoliths can be easily achieved using the functional monomers introduced in the polymerization process or the unreacted vinyl groups present in the polymeric matrix. This control has allowed the preparation of monolithic Supported Ionic Liquid-like Phases (m-SILLPs) with excellent morphological properties. These m-SILLPs have been studied as supports for large biomolecules. Bioadsorption studies show that the adsorbed amount of protein reaches values as high as 150-200 mg of protein per gram of support.


      PubDate: 2014-10-12T07:25:25Z
       
  • Editors and Editorial Board
    • Abstract: Publication date: November 2014
      Source:Reactive and Functional Polymers, Volume 84




      PubDate: 2014-10-12T07:25:25Z
       
  • Cellulose nanopapers as tight aqueous ultra-filtration membranes
    • Abstract: Publication date: Available online 11 October 2014
      Source:Reactive and Functional Polymers
      Author(s): Andreas Mautner , Koon-Yang Lee , Tekla Tammelin , Aji P. Mathew , Alisyn J. Nedoma , Kang Li , Alexander Bismarck
      Recently, we have demonstrated the use of wood-derived nanocellulose papers, herein termed nanopapers, for organic solvent nanofiltration applications. In this study, we extend the use of these nanopapers to tight ultrafiltration (UF) membranes. The feasibility of such nanopaper-based UF membranes intended for use in water purification is shown. Four types of nanocelluloses, namely bacterial cellulose, wood-derived nanocellulose, TEMPO-oxidized cellulose nanofibrils and cellulose nanocrystals, were used as raw materials for the production of these nanopaper-based membranes. The resulting nanopapers exhibit a transmembrane permeance in the range of commercially available tight UF membranes with molecular weight cut-offs ranging from 6 to 25kDa, which depends on the type of nanocellulose used. These molecular weight cut-offs correspond to average pore sizes of a few nanometres. The rejection performance of the nanopapers is on the border of nanofiltration and UF. We demonstrate that the pore size of the nanopapers can be controlled by using different types of nanocellulose fibrils.


      PubDate: 2014-10-12T07:25:25Z
       
  • Using gelatin protein to facilitate paper thermoformability
    • Abstract: Publication date: Available online 2 October 2014
      Source:Reactive and Functional Polymers
      Author(s): Alexey Khakalo , Ilari Filpponen , Leena-Sisko Johansson , Alexey Vishtal , Arcot R. Lokanathan , Orlando J. Rojas , Janne Laine
      One of the main challenges of fiber-based packaging materials is the relatively poor elongation of cellulose under stress, which limits formability and molding in related products. Therefore, in this investigation we first used cellulose thin films and surface sensitive tools such as quartz crystal microbalance (QCM-D), surface plasmon resonance (SPR) and X-ray photoelectron spectroscopy (XPS) to evaluate the cellulose-gelatin interactions. It was found that the highest adsorption of gelatin onto cellulose occurred at the isoelectric pH of the protein. Based on this and other results, a gelatin loading is proposed to facilitate molecular and surface interactions and, thus to improve the formability of cellulose-based materials in paper molding. Aqueous gelatin solutions were sprayed on the surface of wet webs composed of softwood fibers and the chemical and mechanical changes that occurred were quantified. Upon gelatin treatment the elongation and tensile strength of paper under unrestrained drying was increased by ∼50% (from ∼10 to up to 14%) and by ∼30% (from 59 to 78 Nm/g), respectively. The mechanical performance of gelatin-treated fibres was further improved by glutaraldehyde-assisted cross-linking. The proposed approach represents an inexpensive and facile method to improve the plasticity of fibre networks, which otherwise cannot be processed in the production of packaging materials by direct thermoforming.


      PubDate: 2014-10-08T06:47:22Z
       
  • pH-triggered phase inversion and separation of hydrophobised bacterial
           cellulose stabilised Pickering emulsions
    • Abstract: Publication date: Available online 2 October 2014
      Source:Reactive and Functional Polymers
      Author(s): Koon-Yang Lee , Jonny J. Blaker , Jerry Y.Y. Heng , Ryo Murakami , Alexander Bismarck
      The pH-triggered transitional phase behaviour of Pickering emulsions stabilised by hydrophobised bacterial cellulose (BC) is reported in this work. Neat BC was hydrophobised via esterification with acetic (C2-), hexanoic (C6-) and dodecanoic (C12-) acids, respectively. We observed that C6- and C12-BC stabilised emulsions exhibited a pH-triggered reversible transitional phase separation. Water-in-toluene emulsions consisting of 60 vol.-% dispersed phase stabilised by C6- and C12-BC water-in-oil (w/o) emulsions were produced at pH 5. Lowering the pH of the aqueous phase to 1 did not affect the emulsion type. Increasing the pH to 14, however, caused the emulsions to phase separate. This phase separation was caused by electrostatic repulsion between modified BC as a result of dissociable acidic surface groups at high pH, which lowered the surface coverage of the water droplets. When the pH was re-adjusted to 1 again, w/o emulsions re-formed for C6- and C12-BC stabilised Pickering emulsions. C2-BC stabilised emulsions, on the other hand, underwent an irreversible pH-triggered transitional phase separation and inversion. This difference in phase behaviour between C2-BC and C6-/C12-BC was attributed to the hydrolysis of the ester bonds of C2-BC at high pH. This hypothesis is in good agreement with the measured degree of surface substitution (DSS) of modified BC after the pH-triggered experiments. The DSS of C2-BC decreased by 20% whilst the DSS remained constant for C6- and C12-BC.


      PubDate: 2014-10-08T06:47:22Z
       
  • Synthesis of soy protein-lignin nanofibers by solution electrospinning
    • Abstract: Publication date: Available online 2 October 2014
      Source:Reactive and Functional Polymers
      Author(s): Carlos Salas , Mariko Ago , Lucian A. Lucia , Orlando J. Rojas
      Nanofibers were produced by electrospinning aqueous alkaline solutions containing different mass ratios of soy protein and lignin in the presence of poly(ethylene glycol) coadjutant, all of which presented shear thinning behavior. SEM revealed that the addition of polyethylene oxide as a coadjutant indeed facilitated the formation of defect-free fibers whose diameter increased with lignin concentration, in the range between ≈ 124 and ≈ 400 nm. Favorable interactions between lignin and soy protein were identified from data provided by differential scanning calorimetry. In addition, an increased hydrogen bonding and the loss of secondary structure of the proteins as the lignin concentration increased were observed from the disappearance of amide II (∼1500 cm-1) and III (∼1400-1200 cm-1) bands and a red shift of amide I band in the FT-IR spectrum. The unfolding of the protein contributed to a better interaction with lignin macromolecules, which further improved the electrospinning process. It is concluded that mixtures of lignin and soy proteins, two major renewable resources with interesting chemical features, are suitable for the development of composite sub-micron fibers.
      Graphical abstract image

      PubDate: 2014-10-08T06:47:22Z
       
  • A preliminary assay of the potential of soy protein isolate and its
           hydrolysates to provide interfiber bonding enhancements in lignocellulosic
           furnishes
    • Abstract: Publication date: Available online 2 October 2014
      Source:Reactive and Functional Polymers
      Author(s): Abdus Salam , Lucian A. Lucia , Hasan Jameel
      Soy protein isolate (SPI) was extracted from soy flour and hydrolyzed with hydrochloric acid, sodium hydroxide, and enzyme, separately, to provide a series of hydrolysates. The SPI and its hydrolysis products were later cross-linked with ethylendiaminetetraacetic acid (EDTA) in the presence of sodium hypophosphite (SPH) after which they were complexed to chitosan as part of an on-going general chemical strategy in our laboratories to improve their incorporation into an old corrugated container (OCC) matrix and thus increase inter-fiber bonding. Approximately 2% SPI-EDTA-chitosan and hydrolyzed SPI-EDTA-chitosan additives by mass (OCC-based slurry) were thoroughly mixed before generating a sheet for physical testing. The tensile and burst indices of the SPI-EDTA-chitosan additive-treated OCC pulp sheet increased 46.3 and 61.85%, respectively, while the inter fiber bonding of SPI-EDTA-chitosan additive-treated OCC pulp sheet increased 74.86% compared to the control, albeit having a decreased tear strength and roughness, with significantly increased gloss. The additive-treated pulp sheet was characterized by thermogravimetric analysis (TGA), dynamic mechanical analysis (DMA), and ATR to provide evidence for product synthesis.


      PubDate: 2014-10-08T06:47:22Z
       
  • Biopolymeric matrices made of carrageenan and corn starch for the
           antioxidant extracts delivery of Cuban red propolis and yerba mate
    • Abstract: Publication date: Available online 2 October 2014
      Source:Reactive and Functional Polymers
      Author(s): Liliam Chang-Bravo , Alex López-Córdoba , Miriam Martino
      The design of biopolymeric matrices for the delivery of bioactive compounds constitutes a useful strategy to prevent the spoilage of food products. In the current work, carrageenan–starch films with antioxidant extracts of Cuban red propolis and yerba mate were prepared by casting. The morphological analysis by SEM showed a more homogeneous structure for the yerba mate films in comparison with the propolis ones. The incorporation of the natural extracts affected the dynamic-mechanical behavior of the films, whereas their crystallinity degrees were maintained. FTIR analysis showed stronger interactions of the polymer matrix with the propolis extract than with the yerba mate one. The films exhibited differences in their mechanical properties; higher tensile strength values were obtained for the yerba mate films than for the propolis samples. However, the last films exhibited higher elongation at break. Both matrices showed good stability of the active compounds along 6 months of storage at 75% RH and 23 °C. After this time, the samples showed an increase in their DPPH scavenging activity. The release behavior of the phenolic compounds from the films in an aqueous medium was assayed finding significant differences (p <0.05) between release rates of both extracts.


      PubDate: 2014-10-08T06:47:22Z
       
  • Poly(vinylidene fluoride) (PVDF) Membranes for Fluid Separation
    • Abstract: Publication date: Available online 5 October 2014
      Source:Reactive and Functional Polymers
      Author(s): Jing Ji , Fu Liu , N. Awanis Hashim , M.R. Moghareh Abed , Kang Li
      The importance of Poly(vinylidene fluoride) (PVDF) as a membrane material has long been recognised in many membrane processes. Compared to other types of polymeric membranes, the PVDF membranes have received great attention because of its outstanding properties including high hydrophobicity, thermal stability, chemical resistance and excellent mechanical strength. This article provides an overview of recent development in PVDF membrane processes, focussing on the commercial PVDF membrane products for water and wastewater treatment and possible applications of PVDF membranes in areas such as membrane based gas absorption and membrane distillation where no substantial commercial PVDF membrane processes are available so far.


      PubDate: 2014-10-08T06:47:22Z
       
  • The effect of cellulose nanowhiskers on the flexural properties of
           self-reinforced polylactic acid composites
    • Abstract: Publication date: Available online 28 September 2014
      Source:Reactive and Functional Polymers
      Author(s): Kazi M. Zakir Hossain , Reda M. Felfel , Chris D. Rudd , Wim Thielemans , Ifty Ahmed
      Self-reinforced polylactic acid (SR PLA) composites incorporating cellulose nanowhiskers (CNWs) were produced by coating orientated PLA fibres with a polyvinyl acetate (PVAc)-CNW mixture as a binder prior to hot compaction at 95°C. PLA fibres were produced with an average diameter of 11 (± 0.9) μm via a melt-drawing process at 180°C. Scanning electron microscopy (SEM) images revealed that the CNWs imparted roughness to the PLA fibre surface. Cross-sectional examination of the SR PLA composites after hot-pressing confirmed that the PLA fibres had maintained their morphology. Incorporation of 8 wt% CNWs within the SR-PLA composites revealed an increase in their flexural strength (48%) and modulus (39%) compared to the control composite (flexural strength∼82 MPa and modulus∼3.9 GPa). In addition, whilst the control SR-PLA composite revealed quite brittle characteristics, the addition of CNWs and PVAc gave the self-reinforced composite a more ductile behaviour.
      Graphical abstract image

      PubDate: 2014-10-02T05:28:32Z
       
  • Functionalization of polymeric materials as a high performance membrane
           for direct methanol fuel cell: A review
    • Abstract: Publication date: Available online 28 September 2014
      Source:Reactive and Functional Polymers
      Author(s): N. Awang , A.F. Ismail , J. Jaafar , T. Matsuura , H. Junoh , M.H.D. Othman , M.A. Rahman
      A coherent review on the advanced Proton exchange membranes (PEMs) for direct methanol fuel cell (DMFC) application and the future direction in the development of a high performance polymeric membrane for DMFC were discussed in this paper. PEMs have a profound influence on performance of DMFC. The PEMs are categorized into five groups which are partially fluorinated, perfluorinated ionomers, acid-base complexes, non-fluorinated ionomers, hydro carbon and aromatic polymers. Many researchers have investigated the functionalization methods on the PEMs to solve methanol crossover problem while obtaining low electronic conductivity, high proton conductivity, low electro osmotic drag coefficient, high mechanical properties and good chemical and thermal stability. Including in this review, fabrication of PEM using electrospinning process coupled with the promising functionalized polymeric materials which were known to be the most important initiatives at present in order to further expand the full potential of DMFC performance.


      PubDate: 2014-10-02T05:28:32Z
       
  • Study of synthesis parameters and active layer morphology of interfacially
           polymerized polyamide-polysulfone membranes
    • Abstract: Publication date: Available online 30 September 2014
      Source:Reactive and Functional Polymers
      Author(s): Sanne Hermans , Roy Bernstein , Alexander Volodin , Ivo F.J. Vankelecom
      Thin film composite (TFC) polyamide membranes were prepared on a polysulfone support membrane and the effect of various synthesis conditions on the active layer morphology, the physicochemical properties and the membrane performance was investigated. The support membrane porosity factor had a significant effect on the TFC membrane performance. A polyamide top layer was formed within 15 s of reaction. Prolonging the reaction time, although resulting in a thicker active layer, only had a minor influence on the membrane performance. This highlights the importance of the incipient layer of the polyamide structure on its performance. The addition of both a surfactant and a base to the amine solution resulted in a change of the active layer morphology and an improved performance. The effect of additives was attributed to changes in the polymerization mechanism. In addition, it was demonstrated that curing at 50°C resulted in an improved membrane performance, due to more cross-linking of the active layer. Curing at higher temperatures deteriorated the structure of the support membrane. This research shows that the TFC membrane performance is well correlated with the changes in the active layer morphology, measured using SEM, AFM and TEM; whereas only minor changes in the physicochemical characteristics of the membranes were detected by zeta potential and ATR-FTIR spectroscopy when the same synthesis parameters were varied.


      PubDate: 2014-10-02T05:28:32Z
       
  • A review on lignin-based polymeric, micro- and nano-structured materials
    • Abstract: Publication date: Available online 28 September 2014
      Source:Reactive and Functional Polymers
      Author(s): Antoine Duval , Martin Lawoko
      Next to cellulose, lignin is the second most abundant biopolymer, and the main source of aromatic structures on earth. It is a phenolic macromolecule, with a complex structure which considerably varies depending on the plant species and the isolation process. Lignin has long been obtained as a by-product of cellulose in the paper pulp production, but had rather low added-value applications. Changes in the paper market have however stimulated the need to focus on other applications for lignins. In addition, the emergence of biorefinery projects to develop biofuels, bio-based materials and chemicals from carbohydrate polymers should also generate large amounts of lignin with the potential for value addition. These developments have brought about renewed interest in the last decade for lignin and its potential use in polymer materials. This review covers both the topics of the direct use of lignin in polymer applications, and of the chemical modifications of lignin, in a polymer chemistry perspective. The future trend toward micro- and nanostructured lignin-based materials is then addressed.


      PubDate: 2014-10-02T05:28:32Z
       
  • Reactive Phase Inversion for Manufacture of Asymmetric Poly (ether imide
           sulfone) Membranes
    • Abstract: Publication date: Available online 28 September 2014
      Source:Reactive and Functional Polymers
      Author(s): Taghreed A. Jalal , Iran D. Charry Prada , Russel Tayouo , Emmanuel P. Giannelis , Suzana P. Nunes
      Poly (ether imide sulfone) membranes were manufactured by combining phase inversion and functionalization reaction between epoxy groups and amine modified polyether oligomers (Jeffamine) or TiO2 nanoparticles. Polysilsesquioxanes containing epoxy functionalities were in-situ grown in the casting solution and made available for further reaction with amines in the coagulation/annealing baths. The membranes were characterized by field emission scanning electron microscopy, porosimetry and water flux measurements. Water permeances up to 1500 l m-2 h-1 bar-1 were obtained with sharp pore size distribution and a pore diameter peak at 66 nm, confirmed by porosimetry, which allowed 99.2% rejection of γ-globulin. Water flux recovery of 77.5% was achieved after filtration with proteins. The membranes were stable in 50:50 dimethylformamide/water, 50:50 N-methyl pyrrolidone/water and 100% tetrahydrofuran. The possibility of using similar concept for homogeneous and stable attachment of nanoparticles on the membrane surface was demonstrated.


      PubDate: 2014-10-02T05:28:32Z
       
  • Cross-linked PAN-based thin-film composite membranes for non-aqueous
           nanofiltration
    • Abstract: Publication date: Available online 30 September 2014
      Source:Reactive and Functional Polymers
      Author(s): Liliana Pérez-Manríquez , Jamaliah Aburabi’e , Pradeep Neelakanda , Klaus-Viktor Peinemann
      A new approach on the development of cross-linked PAN based thin film composite (TFC) membranes for non-aqueous application is presented in this work. Polypropylene backed neat PAN membranes fabricated by phase inversion process were cross-linked with hydrazine to get excellent solvent stability towards dimethylformamide (DMF). By interfacial polymerization a selective polyamide active layer was coated over the cross-linked PAN using N,N’-diamino piperazine (DAP) and trimesoyl chloride (TMC) as monomers. Permeation and molecular weight cut off (MWCO) experiments using various dyes were done to evaluate the performance of the membranes. Membranes developed by such method show excellent solvent stability towards DMF with a permeance of 1.7 L/m2 h bar and a molecular weight cut-off of less than 600 Da.


      PubDate: 2014-10-02T05:28:32Z
       
  • Thin-film composite crosslinked polythiosemicarbazide membranes for
           organic solvent nanofiltration (OSN)
    • Abstract: Publication date: Available online 22 September 2014
      Source:Reactive and Functional Polymers
      Author(s): Jamaliah Aburabie , Pradeep Neelakanda , Madhavan Karunakaran , Klaus-Viktor Peinemann
      In this work we report a new class of solvent stable thin-film composite (TFC) membrane fabricated on crosslinked polythiosemicarbazide (PTSC) as substrate that exhibits superior stability compared with other solvent stable polymeric membranes reported up to now. Integrally skinned asymmetric PTSC membranes were prepared by the phase inversion process and crosslinked with an aromatic bifunctional crosslinker to improve the solvent stability. TFC membranes were obtained via interfacial polymerization using trimesoylchloride (TMC) and diaminopiperazine (DAP) monomers. The membranes were characterized by Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM) and contact angle measurement. The membranes exhibited high fluxes towards solvents like tetrahydrofuran (THF), dimethylformamide (DMF) and dimethylsulfoxide (DMSO) ranging from 12-25 L/m2 h at 5 bar with a molecular weight cut off (MWCO) of around 1000 g/mol. The PTSC-based thin-film composite membranes are very stable towards polar aprotic solvents and they have potential applications in the petrochemical and pharmaceutical industry.


      PubDate: 2014-09-26T04:53:21Z
       
  • Targeted Gas Separations through Polymer Membrane Functionalization
    • Abstract: Publication date: Available online 17 September 2014
      Source:Reactive and Functional Polymers
      Author(s): Melinda L. Jue , Ryan P. Lively
      Gas separation membranes have been studied for several decades and are starting to find commercial acceptance.This review will focus on polymer functionalization to improve gas separation performance, namely, permeability, permselectivity, or both. The review will cover both “diffusivity controlled” functionalization and “solubility controlled” functionalization; each strategy refers to the different mode of gas transport through the membrane.Diffusivity controlled functionalization strategies mainly involve control over free volume elements in amorphous polymers via promotion or inhibition of chain packing through functional groups. As such, the effects of this functionalization are typically confined to the well-known selectivity/permeability tradeoff. Solubility controlled modification strategies utilize functional groups that have strong chemical interactions with some of the penetrant molecules and offers an enhanced solution-diffusion or a non-solution-diffusion permeation pathway.This functionalization can potentially exceed the Robeson upper bound, but is often challenged by impurities and deactivation of the chemical functionality.


      PubDate: 2014-09-22T04:17:30Z
       
  • Synthesis and characterization of poly(tetramethylsilarylenesiloxane)
           derivatives bearing benzodithiophene moieties
    • Abstract: Publication date: Available online 18 September 2014
      Source:Reactive and Functional Polymers
      Author(s): Hitoshi Hanamura , Ryoichi Hattori , Ryo Maruyama , Nobukatsu Nemoto
      Poly(tetramethylsilarylenesiloxane) derivatives bearing benzo[1,2-b;4,5-b’]dithiophene (P1) and benzo[2,1-b;3,4-b’]dithiophene (P2) moieties were prepared via polycondensation of the corresponding disilanol monomers, that is, 2,6-bis(dimethylhydroxysilyl)benzo[1,2-b;4,5-b’]dithiophene (M1) and 2,7-bis(dimethylhydroxysilyl)benzo[2,1-b;3,4-b’]dithiophene (M2), respectively. It was deduced that P1 is a crystalline polymer while P2 is an amorphous one from the results of differential scanning calorimetry (DSC). Bathochromic and hyperchromic effects were observed in the absorption and fluorescence spectra when dimethylsilyl substituents were introduced on the benzo[1,2-b;4,5-b’]dithiophene and benzo[2,1-b;3,4-b’]dithiophene skeletons. The fluorescence quantum yields (Φ Fs) were not improved by the introduction of dimethylsilyl groups onto the benzo[1,2-b;4,5-b’]dithiophene and benzo[2,1-b;3,4-b’]dithiophene skeletons, whereas the improvement in the Φ Fs was remarkable in the case of poly(tetramethylsilarylenesiloxane) derivatives that possessed the corresponding fused benzene ring systems, i.e., poly(tetramethyl-2,6-silanthrylenesiloxane) and poly(tetramethyl-1,8-silphenanthrylenesiloxane).


      PubDate: 2014-09-22T04:17:30Z
       
  • Biodegradable hybrid poly(3-hydroxyalkanoate)s networks through
           silsesquioxane domains formed by efficient UV- Curing
    • Abstract: Publication date: Available online 19 September 2014
      Source:Reactive and Functional Polymers
      Author(s): C. Lorenzini , D.L. Versace , J. Babinot , E. Renard , V. Langlois
      New bridged silsesquioxanes derived from poly(3-hydroxyalkanoate)s were synthesized, according to the sol-gel process, by conventional acidic, basic hydrolysis or by UV-curing in presence of cationic photo-initiator to compare the properties of the resulting networks. First, microwave assisted alcoholysis in the presence of ethylene glycol provided an efficient method for engineering PHA-diols. These well-defined oligoesters have been derivatized into telechelic bis-triethoxysilyl precursors and sol gel chemistry was employed as cross-linking reaction method. The thermal stability of PHA was improved by incorporation into the silica network, except in basic condition, due to simultaneous formation of the network and the degradation of the PHA backbone. The glass-transition temperatures of the networks prepared in acidic conditions increased from -14°C up to +16°C. 29Si NMR measurements also showed that UV curing catalyzed by cationic photo-initiator promotes a high degree of condensation in the organic network that became totally amorphous. This method is a straightforward way applied at room temperature in a very short reaction time (i.e. 300 s) to obtain crosslinked network that remain partially biodegradable by lipase.


      PubDate: 2014-09-22T04:17:30Z
       
  • Water vapor and CO2 transport through amine-containing facilitated
           transport membranes
    • Abstract: Publication date: Available online 20 September 2014
      Source:Reactive and Functional Polymers
      Author(s): Zi Tong , Varun K. Vakharia , Michael Gasda , W.S. Winston Ho
      Amine-containing CO2 facilitated transport membranes have great potential to be applied for hydrogen purification from synthesis gas. In some applications, the humidity of the retentate stream is required as well as the purity of hydrogen. The membranes are highly hydrophilic, and they exhibit not only high CO2 permeance but also high water vapor permeance. In this work, the transport of water vapor and CO2 through the membranes composed of an amine-containing selective layer and a microporous polysulfone substrate was investigated. From the experiments conducted, water vapor permeance appeared to be independent of the selective layer thickness, indicating that the substrate is the controlling factor of the mass transfer resistance to water vapor transport. Moreover, water vapor permeance appeared to reduce linearly with increasing the number of the substrate layers. But, CO2 permeance and CO2/H2 selectivity did not change significantly as the number of the substrate layers increased. These results indicated that the CO2 separation performance is governed by the selective layer as expected. In addition, the membranes synthesized from Lupamin® containing 34% polyvinylamine and 66% salt (sodium formate) demonstrated better CO2 separation performance than those from pure polyvinylamine, presumably due to better water retention capability of the salt than polyvinylamine.


      PubDate: 2014-09-22T04:17:30Z
       
  • Influence of mechanical treatments on the properties of cellulose
           nanofibers isolated from microcrystalline cellulose
    • Abstract: Publication date: Available online 20 September 2014
      Source:Reactive and Functional Polymers
      Author(s): Davide Bandera , Janak Sapkota , Sébastien Josset , Christoph Weder , Philippe Tingaut , Xin Gao , E. Johan Foster , Tanja Zimmermann
      The possibility of preparing cellulose whiskers-like materials by mechanical treatment of commercially available microcrystalline cellulose (MCC) was explored. High shear homogenization, grinding with a supermass colloider, and hammer-milling were the processes selected to disintegrate the MCC, which yielded F-MCC, G-MCC and H-MCC, respectively. Processing aqueous dispersions with high solid content allowed for the production of cellulose particles with greatly reduced dimensions. Morphological characterization revealed that homogenization and grinding reduced the particle size more effectively than hammer-milling, although the disintegration was incomplete in all cases. The reinforcing potential of the materials was evaluated against commercially available whiskers by using the various particles as fillers to mechanically reinforce hydroxypropylcellulose. Nanocomposite films containing 5, 10, or 20 wt.% of the filler were prepared and the mechanical properties were characterized. The results show that H-MCCs are just slightly better than the original MCC, whereas F-MCC and G-MCC performed similar to whiskers at 10 wt.% loading, despite the presence of a fraction of micrometer-sized particles. It is therefore reasonable to envision the use of the more easily produced F-MCC and G-MCC as replacement of cellulose whiskers in some applications.


      PubDate: 2014-09-22T04:17:30Z
       
  • Transforming large molecular weight pectin and chitosan into oral protein
           drug nanoparticulate carrier
    • Abstract: Publication date: Available online 16 September 2014
      Source:Reactive and Functional Polymers
      Author(s): Syed Othman Syed Mohamad Al-Azi , Yvonne Tze Fung Tan , Tin Wui Wong
      Polymeric nanoparticle formation is characterized by high risks of premature drug leaching and low drug encapsulation efficiency. This is aggravated by slow nanoparticle formation by large molecular weight polymers due to their slow diffusion kinetics in the reaction medium. This study investigated model protein drug insulin encapsulation by large molecular weight pectin and chitosan. The nanoparticles were prepared through pectin-chitosan coacervation and when necessary, together with pectin or chitosan crosslinking by calcium or tripolyphosphate ions in the same process. The formed particles were nanospray-dried when required. The size, zeta potential, morphology, drug content, drug association efficiency, polymer-polymer and drug-polymer interaction in particulate matrix were examined. The pectin-chitosan nanoparticles were able to encapsulate insulin substantially only if these nanoparticles were formed with rapid particle aggregation into micromatrices as a result of particle surfaces attracting the oppositely charged polymer chains via crosslinking as well as coacervation processes. The particulate aggregation level of micromatrices can be reduced via nanospray drying. Small discrete nanoparticles were obtainable from micromatrices.


      PubDate: 2014-09-17T03:34:23Z
       
  • Composite Membranes from Polyacrylonitrile with
           Poly(N,N-dimethylaminoethyl methacrylate)-grafted Silica Nanoparticles as
           Additives
    • Abstract: Publication date: Available online 16 September 2014
      Source:Reactive and Functional Polymers
      Author(s): Suo-Hong Zhi , Ran Deng , Jun Xu , Ling-Shu Wan , Zhi-Kang Xu
      Polyacrylonitrile (PAN)-based composite membranes were prepared by immersion precipitation method by using poly(N,N-dimethylaminoethyl methacrylate)-grafted silica (PDMAEMA@SiO2) nanoparticles as hydrophilic additives. The molecular weight of PDMAEMA were controlled by the surface initiated atom transfer radical polymerization of N,N-dimethylaminoethyl methacrylate on SiO2 nanoparticles. The synthesized nanoparticles have a typical core-shell structure as characterized in detail by FT-IR, TEM, DLS and GPC. The prepared PAN-based composite membranes have higher porosity and water permeation flux than those of the pure PAN membranes. They also show high rejection (⩾90%) to bovine serum albumin and high flux recovery ratio (⩾90%) to water permeation. These improved performances are attributed to the good hydrophilicity of PDMAEMA@SiO2 nanoparticles. The results suggest that PDMAEMA@SiO2 nanoparticles are suitable for the property optimization of PAN-based composite membranes.


      PubDate: 2014-09-17T03:34:23Z
       
  • Positively charged loose nanofiltration membrane grafted by diallyl
           dimethyl ammonium chloride (DADMAC) via UV for salt and dye removal
    • Abstract: Publication date: Available online 16 September 2014
      Source:Reactive and Functional Polymers
      Author(s): Fu Liu , Bi-rong Ma , Dong Zhou , Li-Jing Zhu , Yin-Yi Fu , Li-xin Xue
      A novel positively charged loose nanofiltration (NF) membrane was fabricated feasibly by UV-induced photografting polymerization of diallyl dimethyl ammonium chloride (DADMAC) on polysulfone ultrafiltration membrane. A possible reaction mechanism was proposed that a linear chain structure and/or pyrrolelike five-membered nitrogen heterocycles structure on the side chain were grafted to form the active barrier layer. NF membrane demonstrated a looser average pore size of 8.6 nm and positive charges surface. Owing to the nanoscale ultrathin nanoscale barrier layer and the combination of Donnan exclusion and steric hindrance, NF membrane exhibited good hydrophilicity, a high pure flux of 60 L/m2h (0.5 MPa), a good salt rejection to Mg2+ (90.8%), Al3+ (94.0%), Ca2+ (91.5%), and a high dye rejection to methylene blue (99.4%) and congo red (100.0%) respectively. The salts rejection of NF membrane to different salts followed the order of AlCl3>CaCl2>MgCl2>NaCl>LiCl>MgSO4>Na2SO4. NF membrane showed certain fouling resistance to seawater and BSA solution. The grafting polymerization kinetics were comprehensively investigated including irradiation time, monomer concentration and irradiation intensity. X-ray Photoelectron Spectroscopy (XPS), scanning electron microscopy (SEM), atomic force microscopy (AFM) and contact angle measurement were employed to investigate membrane chemistry, morphologies, and hydrophilicity.


      PubDate: 2014-09-17T03:34:23Z
       
  • Synthesis of Perylene Dianhydride-incorporated Main Chain Polyimides and
           Sequential Structural Transformation through a Dipolar Cycloaddition
    • Abstract: Publication date: Available online 10 September 2014
      Source:Reactive and Functional Polymers
      Author(s): Mieon Choi , Jung Yun Do
      Perylene dianhydride (PDA)-incorporated polyimides were prepared. The perylene unit in the polyimide was thermally converted to the corresponding N-heterocyclic polyarene unit through a Diels-Alder reaction. The monomer, 2,2-bis(3-amino-4-hydroxyphenyl) hexafluoropropane (6FAP), was modified via O-alkylation to improve the solubility of the polymer. 2-Ethylhexyl-attached 6FAP yielded a soluble copolyimide that contained ca. 70 mol% PDA using pyromellitic dianhydride. The perylene unit of the copolyimide transformed to a polyarene unit through the dipolar cycloaddition of 4-aryl-1,2,4-triazole-3,5-dione (TAD) and maleic anhydride. The perylene transformation of the polyimide occurred with 50% conversion with maleic anhydride and quantitatively with TAD. The PDA-copolymer exhibited a spectral blue-shift and red-shift by maleic anhydride and TAD, respectively.


      PubDate: 2014-09-13T02:55:15Z
       
  • In situ oxidation-induced gelation of poly(aspartic acid) thiomers
    • Abstract: Publication date: Available online 6 September 2014
      Source:Reactive and Functional Polymers
      Author(s): Benjámin Gyarmati , Enikő Krisch , András Szilágyi
      In situ gelling poly(aspartic acid) thiomers are investigated to demonstrate their potential application in the development of injectable formulations. The chemical stability of the thiomer solutions is measured against air to determine the maximum storage time of the solution before injection. Hydrogels exhibit considerably large storage moduli after the chemical oxidation of the low-viscosity thiomer solution. The gelation time can be controlled within 2 to 6 min, which is advantageous for injection because the thiomer solution and the oxidizing agent can be mixed safely in a two-chamber system before injection into the desired site of the body.
      Graphical abstract image

      PubDate: 2014-09-08T02:15:09Z
       
  • Synthesis and characterization of chitosan hydrogels cross-linked with
           dicarboxylic acids
    • Abstract: Publication date: Available online 6 September 2014
      Source:Reactive and Functional Polymers
      Author(s): N.E. Valderruten , J. Valverde , F. Zuluaga , E. Ruiz-Durantez
      Chitosan hydrogels cross-linked with dicarboxylic acids were prepared. Succinic, glutaric and adipic acid were used as cross-linking agents, the goal being to compare the effect of the length of the chain on the behavior of the material obtained. The swelling properties were studied at different pHs and temperatures, and it was discovered that these properties depend particularly on the pH of the environment. Creep-recovery and stress-relaxation studies were performed to determine mechanical properties and the chitosan/succinic acid hydrogels exhibited a completely viscous behavior. Thermal studies were carried out using differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA). DSC results revealed that the materials obtained are completely amorphous. Acetaminophen was used as a positive control for the release kinetics studies. Upon fitting the results to a specific mathematical model, it was determined that the release process is controlled by diffusion and relaxation of the polymer network.


      PubDate: 2014-09-08T02:15:09Z
       
  • Temperature- and pH-sensitive membrane formed from blends of
           poly(vinylidene fluoride)-graft-poly(N-isopropylacrylamide) and
           poly(acrylic acid) microgels
    • Abstract: Publication date: Available online 28 August 2014
      Source:Reactive and Functional Polymers
      Author(s): Xi Chen , Bowu Zhao , Peng Han , Weigui Fu , Li Chen
      Temperature- and pH-responsive membranes prepared from blends of poly(vinylidene fluoride)-graft-poly(N-isopropylacrylamide)(PVDF-g-PNIPAM) copolymer and poly(acrylic acid) (PAA) microgels in N, N-dimethylformamide (DMF) solution by phase inversion method. PAA microgels help PNIPAM chains largely enrich onto membrane surface. Furthermore, adding PAA microgels increases the porous size, porosity and hydrophilic property of the blend membrane. The membranes show temperature-sensitivity between 30 to 35°C, and pH- sensitivity between pH 3 and 5 on permeating aqueous solutions. Meanwhile, the blend membranes keep good antifouling property even if one of the hydrophilic components becoming hydrophobic in response to temperature or pH stimuli, which is superior to single-sensitive PVDF membrane.


      PubDate: 2014-09-03T00:59:50Z
       
  • Editors and Editorial Board
    • Abstract: Publication date: October 2014
      Source:Reactive and Functional Polymers, Volume 83




      PubDate: 2014-09-03T00:59:50Z
       
  • Water-soluble oxidized starch in complexation of Fe(III), Cu(II), Ni(II)
           and Zn(II) ions
    • Abstract: Publication date: October 2014
      Source:Reactive and Functional Polymers, Volume 83
      Author(s): Sanna Komulainen , Estibaliz Diaz , Johanna Kärkkäinen , Jouni Pursiainen , Paavo Perämäki , Marja Lajunen
      The structure of the bromate-oxidized wheat starch (OS) contains partly opened glucose units with carbonyl and carboxyl groups at C2-, C3- or C6-positions. OS with a variable degree of oxidation (DO) was studied in alkaline conditions as a water-soluble complexing agent for Fe(III), Cu(II), Ni(II) and Zn(II) ions, which are common in various wastewaters. Complexation was studied by inductively coupled plasma-optical emission spectrometry (ICP–OES) in a single metal ion or multi-metal ion solutions. The DO affected the efficiency of the complexation with metal ions. OS with the high DO (carboxyl and carbonyl DO of 0.72 and 0.23, respectively) complexed and held Fe(III) or Zn(II) ions in a soluble form effectively in 0.5mM single ion alkaline solution with the molar ratio of 0.65:1 of oxidized starch-to-metal ion (OS-to-M). The OS-to-M molar ratio of 1.3:1 was required to form a soluble complex with Cu(II) or Ni(II) ions. These complexes were thermally stable at the temperature range of 20–60°C. OS with the low DO (carboxyl and carbonyl DO 0.47 and 0.17, respectively) complexed Zn(II) ions highly, Cu(II) and Ni(II) ions poorly and Fe(III) ions only partly. In the multi-metal ion solution of OS the solubility of these metal ions improved with the increasing DO of starch, which followed the same tendency as was observed in the single metal ion systems. The increased molar ratio of OS-to-M improved the complexation and solubility of the metal ions in all multi-metal ion series. As the soluble multi-metal ion complexes were reanalyzed after 7days, all solutions had kept the high complexation and solubility of metal ions (ca. 90%). Complexation by OS did not show a selective binding of the ions in the multi-metal ion solution. It was concluded that the flexible, opened ring structure units of OS prevented the selective binding to metal ions but made the complexes highly stable. Titrimetric studies of OS–Fe(III) complexation showed that each anhydroglucose unit of OS had more than one coordination site and as the content of OS increased, the free sites coordinated to Fe(III) ions and formed cross-linked starch structures.


      PubDate: 2014-09-03T00:59:50Z
       
  • Donor–acceptor–donor polymers utilizing pyrimidine-based
           acceptors
    • Abstract: Publication date: October 2014
      Source:Reactive and Functional Polymers, Volume 83
      Author(s): Katie L. Winkel , Jamie R. Carberry , Leslie M. Wood , Makda Araya , Zachary W. Iszard , Travis Cantu , Benjamin Martin , Xiaopeng Li , Jennifer A. Irvin
      Pyrimidine acceptor groups were coupled with thienyl, 3,4-ethylenedioxythienyl (EDOT), and 3,4-(2,2-dibutylpropylenedioxy)thienyl (ProDOT-Bu2) donor groups in an attempt to synthesize stable n-doping polymers. Monomers were synthesized using a triorganoindium coupling reaction and characterized using nuclear magnetic resonance spectroscopy, X-ray crystallography, and electrochemical characterization techniques. The monomers undergo oxidative polymerization, with the alkylenedioxy-functionalized rings reducing oxidation and reduction potentials of monomer and polymer relative to the non-functionalized thiophene analogues, yielding electroactive polymers. The unsymmetrical nature of the monomers leads to unusual redox processes apparent during electrochemical polymerization. The polymer containing ProDOT-Bu2 groups was soluble in chloroform, while the other two polymers were insoluble. Band gaps were 1.6eV for the ProDOT-based polymer and 1.8eV for the EDOT-based polymer, which are comparable to other bisalkylenedioxyarylene-based polymers.


      PubDate: 2014-08-16T23:50:37Z
       
  • Poly(NIPAAm-co-β-cyclodextrin) microgels with drug hosting and
           temperature-dependent delivery properties
    • Abstract: Publication date: Available online 7 August 2014
      Source:Reactive and Functional Polymers
      Author(s): Marieta Constantin , Sanda Bucatariu , Paolo Ascenzi , Bogdan C. Simionescu , Gheorghe Fundueanu
      One of the most important drawbacks of the thermosensitive hydrogels based on N-isopropylacrylamide (NIPAAm) is the lack of functional groups able to specifically bind drugs; moreover, these hydrogels are not biodegradable. In order to overcome these inconveniences, poly(NIPAAm-co-β-cyclodextrin) (poly(NIPAAm-co-β-CD)) microgels were obtained by cross-linking polymerization of the corresponding monomers. β-CD was first functionalized with an appropriate amount of vinyl groups, thus acting both as a co-monomer with hosting properties and as a biodegradable cross-linker. The volume phase transition temperature (VPTT) of the microgels was determined under simulated physiological conditions by measuring the swelling degree and by microcalorimetry. The microgels, due to their small size and high porosity, possess a relative rapid swelling/deswelling rate around the human body temperature. The hydrogels were loaded with the model drug diclofenac by inclusion within cyclodextrin cavity and the release studies were performed under simulated physiological conditions, below and the above the VPTT. In the presence of α-amylase (from Aspergillus Oryzae), microgels have showed a low degradation rate (15% of initial weight after 7 days), the erosion occurring especially at the surface.


      PubDate: 2014-08-12T23:39:34Z
       
  • Synthesis and Optical, Electrical, and Thermoelectric Properties of Sodium
           Salts of Polyanilinesulfonic Acid
    • Abstract: Publication date: Available online 7 August 2014
      Source:Reactive and Functional Polymers
      Author(s): Isao Yamaguchi , Yusuke Sada
      Sodium salts of poly(aniline-5-sulfonic acid) (PAS), The PAS(Na)s, were obtained by the reaction of PAS with NaOH in water. The degree of sodium sulfonation of the PAS(Na)s depended on the feed amount of NaOH. The absorption peak of the PAS(Na)s, corresponding to an exciton transition generated by self-doping in the polymer backbone, decreased with the number of sodium sulfonated units. The PAS(Na)s were subjected to electrochemical oxidation, and the two oxidation peaks shifted to a lower potential as the degree of sodium sulfonation increased. The electrochemical reaction was accompanied by electrochromism. Thermoelectric measurements of the PAS(Na)s suggested that the majority of carriers were holes. The Seebeck coefficients (S’s) of the PAS(Na)s increased as the degree of sodium sulfonation of the polymers increased.


      PubDate: 2014-08-12T23:39:34Z
       
  • Synthesis and properties of polysiloxanes containing mixed functional
           groups
    • Abstract: Publication date: Available online 12 August 2014
      Source:Reactive and Functional Polymers
      Author(s): Hieronim Maciejewski , Joanna Karasiewicz , Agnieszka Dutkiewicz , Michał Dutkiewicz , Katarzyna Dopierała , Krystyna Prochaska
      An effective synthesis of polysiloxanes containing mixed functional groups was carried out using consecutive hydrosilylation of two different olefins. With the functionalization of polysiloxanes, we sought to obtain derivatives containing fluoroalkyl groups (with hydrophobic properties) and reactive groups capable of attaching a polysiloxane to the surface. Glycidyl and trimethoxysilyl groups were chosen for the study. All of the obtained derivatives were isolated and spectroscopically characterized. In the next stage of the study, glass plates were modified with functionalized polysiloxanes, both alone and with added silica sol, and their hydrophobic properties were determined by measuring contact angles. From the results, we determined the effect of functionalized polysiloxane structure on the hydrophobic properties of polysiloxane-modified surfaces.


      PubDate: 2014-08-12T23:39:34Z
       
  • New epoxy thermosets modified with amphiphilic multiarm star polymers as
           toughness enhancer
    • Abstract: Publication date: Available online 6 August 2014
      Source:Reactive and Functional Polymers
      Author(s): Carles Lagunas , Xavier Fernández-Francos , Francesc Ferrando , Marjorie Flores , Àngels Serra , Josep M. Morancho , Josep M. Salla , Xavier Ramis
      The synthesis and characterization of two novel amphiphilic multiarm star polymers with linear polyethylene glycol (PEG) and poly(ε-caprolactone) (PCL) arms and their use as toughening modifiers of epoxy anhydride thermosets are reported. The new star polymers were obtained by partial pegylation of a hyperbranched polyester and subsequent growth of PCL arms. The curing process was studied by calorimetry and thermomechanical analysis, demonstrating the accelerating effect and the influence on gelation of the hydroxyl terminal groups. The curing kinetics was analyzed by model-free and model-fitting methods. The final properties of the resulting materials were determined by thermal and mechanical tests. The addition of the star-like modifiers led only to notable improvement on impact strength in the material containing a 10% of the star with PCL and PEG arms, without compromising glass transition temperature and thermal stability. The morphology of the resulting materials depended on the structure of the toughness modifier used, as demonstrated by electron microscopy, but all modified thermosets obtained showed phase-separated morphologies with nanosized particles.


      PubDate: 2014-08-06T23:08:07Z
       
  • UV-Light Assisted Single Step Route to Functional PEEK Surfaces
    • Abstract: Publication date: Available online 12 July 2014
      Source:Reactive and Functional Polymers
      Author(s): Ahmed Yousaf , Aleeza Farrukh , Zehra Oluz , Eylul Tuncel , Hatice Duran , Sema Yiyit Dogan , Turgay Tekinay , Habib ur Rehaman , Basit Yameen
      Polyether ether ketone (PEEK) is a thermoplastic polymer of high technological relevance and is composed of repeating phenyl ether and benzophenone units. In the present work we will demonstrate the potential of UV irradiation assisted generation of free radicals on the surface benzophenone units to graft a variety of polymer chains on the PEEK surface. Both “grafting-to” and “grafting-from” approaches were explored by using different monomers and polymers. Styrene, butyl acrylate (BA), vinyl phosphonic acid (VPA), acrylic acid (AA), polyacrylic acid (PAA) and monomethoxy terminated oligo(ethylene glycol)methacrylate (MeOEGMA) were successfully utilized for this purpose. The functionalized membranes were characterized by X-ray photoelectron spectroscopy (XPS), attenuated total reflectance Fourier-transformed Infrared (ATR-FTIR) spectroscopy, atomic force microscopy (AFM), and contact angle (CA) goniometry. PAA and PVPA functionalized PEEK surfaces exhibited pH responsive wettability behavior. PAA functionalized PEEK surfaces were further modified with lysine, which led to the controlled surface wettability over a broader pH range as compared to the simple PAA functionalized surface. The grafting with polyMeOEGMA rendered PEEK surface with nonfouling properties against bacterial growth. Employing this highly economical and simple method, the surface properties of PEEK can be modulated and tuned according to a specific application.


      PubDate: 2014-07-28T21:34:15Z
       
  • Preparation, characterisation and properties of sulphoxide modified
           polystyrene resins for solid-phase extraction of PtIV, RuIII and RuIV from
           hydrochloric acid
    • Abstract: Publication date: Available online 12 July 2014
      Source:Reactive and Functional Polymers
      Author(s): Michael Trautmann , Susanne Lubahn , Hans-Jürgen Holdt
      New sulphoxide modified resins were synthesized using poly(styrene-co-divinylbenzene) (PS-DVB) as matrix. Infrared spectroscopy and elemental analysis were used for characterisation. Solid-phase extraction of PtIV, RuIII and RuIV from acidic chloride solutions was performed via batch experiments. Influence of spacer length between sulphoxide and matrix (ethylene, hexamethylene), substitution of sulphoxide (R1: ethyl, hexyl, phenyl) and bead size of PS-DVB (spherical beads: d50<155 μm, d50<80 μm; powder: d50<30 μm) on adsorption was investigated subjected to acidity. Experimental results showed that ethyl substituted sulphoxide immobilised onto ground PS-DVB and hexamethylene spacer exhibited best adsorption properties. Different kinetic models and isotherms were fitted to the experimental data to identify extraction mechanism. PtIV was quantitative sorbed at [HCl]⩽0.1 mol/L whereas RuIII and RuIV sorption ranged between 90-95% at [HCl]⩾5 mol/L. Desorption was reached using a solution of 0.5M thiourea (Tu) in 0.1M HCl at 90°C. Separation of PtIV and RuIII occurred at [HCl]⩽0.1 mol/L whereas PtIV was extracted and RuIII remained in solution. A further separation was achieved by extracting PtIV and RuIV at 5M HCl followed by sequential elution of PtIV with concentrated HCl and RuIV with 0.5M Tu in 0.1M HCl at 90°C.


      PubDate: 2014-07-28T21:34:15Z
       
  • Synthesis and Characterization of Cross-Linked Molecularly Imprinted
           Polyacrylamide for the Extraction/Preconcentration of Glyphosate and
           Aminomethylphosphonic Acid from Water Samples
    • Abstract: Publication date: Available online 12 July 2014
      Source:Reactive and Functional Polymers
      Author(s): Kamilla da Mata , Marcela Zanetti Corazza , Fernanda Midori de Oliveira , Ana Lúcia de Toffoli , César Ricardo Teixeira Tarley , Altair Benedito Moreira
      The present study describes the synthesis of molecularly imprinted polyacrylamide and its applications for the selective adsorption of glyphosate (GP) and its degradation product, aminomethylphosphonic acid (AMPA). The molecularly imprinted polymers (MIPs) were prepared by polymerization in a homogeneous medium, which is known as the “in bulk” method. The reagents used for the synthesis were acrylamide (AAm) as the functional monomer, ethylene glycol dimethacrylate (EGDMA) as the cross-linking reagent, and azobisisobutyronitrile (AIBN) as the radical initiator. The selectivity of the MIPs was evaluated with non-imprinted polymers (NIPs) for each polymer synthesized without the template molecule. Polymer characterization was carried out by thermogravimetry (TG) analysis, Fourier-transform infrared spectroscopy (FT-IR), elemental analysis, and scanning electron microscopy (SEM). The experimental data on the adsorption kinetics were best explained by a pseudo-second-order kinetic model. The Langmuir-Freundlich nonlinear isotherm model for two adsorption sites had the best fit to the experimental data for glyphosate and AMPA. The maximum adsorption capacities were 3.37 and 4.74 mg g-1 for MIP-GP and MIP-AMPA, respectively. According to the relative selectivity (k’) values, higher selectivities for the analytes were observed in aqueous medium for the MIPs than for the NIPs.


      PubDate: 2014-07-28T21:34:15Z
       
  • Fabrication of composition-graded collagen/chitosan-polylactide scaffolds
           with gradient architecture and properties
    • Abstract: Publication date: Available online 21 July 2014
      Source:Reactive and Functional Polymers
      Author(s): Dengke Yin , Hua Wu , Chaoxu Liu , Jun Zhang , Ting Zhou , Jingjing Wu , Ying Wan
      Chitosan-polylactide (CH-PLA) copolymers with various polylactide percentages changing from around 14 to 40 wt% were synthesized. CH-PLAs were then blended with type-II collagen to fabricate layered collagen/CH-PLA scaffolds that are potentially suitable for the applications in articular cartilage repair. Based on combinatorial processing techniques involving layer-supraposition, thermal melting and freeze-drying, two types of stratified collagen/CH-PLA scaffolds were built. The content of collagen inside the scaffolds altered from the top layer to the bottom layer in a trend contrary to that of chitosan. One of them was fabricated using tripolyphosphate (TPP) as a single crosslinker and another type of scaffold was constructed via a dual-crosslinking pathway using TPP and genipin as two crosslinkers in a designated order. These collagen/CH-PLA scaffolds were found to have graded average pore-size and porosity, gradient swelling index and layer-dependent compressive modulus. The resulting scaffolds were thus partially similar to the articular cartilage extracellular matrix in composition, structure and property. In vitro cell culture on some optimized collagen/CH-PLA scaffolds for a period of time up to 3 weeks showed that the scaffolds were able to well support the growth of the seeded cells, suggesting that these collagen/CH-PLA scaffolds have promising potential for articular cartilage repair.


      PubDate: 2014-07-28T21:34:15Z
       
  • Electrochemical synthesis, characterization and capacitive properties of
           novel thiophene based conjugated polymer
    • Abstract: Publication date: Available online 21 July 2014
      Source:Reactive and Functional Polymers
      Author(s): Burcu Çelik , İlhami Çelik , Hacer Dolaş , Hakan Görçay , Yücel Şahin , A.Sezai Saraç , Kadir Pekmez
      In this paper, a novel thiophene based monomer, 1-(pyren-1-yl)-2,5-di(thiophen-2-yl)-1H-pyrrole, PThP, was synthesized and characterized by 1H NMR and 13C NMR spectroscopic methods. The electrochemical behavior and electropolymerization of this novel monomer were performed on pencil graphite electrode (PGE) by cyclic voltammetry. The effect of solvent, dopant, scan number and scan rate on the electropolymerization and properties of the conjugated polymer films were investigated. The capacitive properties of the poly(PThP) films were tested by electrochemical impedance spectroscopy (EIS). The highest specific capacitance value was calculaed for the conjugated polymer modified PGE that was obtained in 0.1 M tetrabutylammonium perchlorate/dichloromethane solution for 30 cycles at 25 mV/s scan rate as 25.45 mF cm-2. The surface morphologies of the conjugated polymer modified electrodes were determined by scanning electron microscopy (SEM).


      PubDate: 2014-07-28T21:34:15Z
       
  • Biodegradable macromolecular conjugates of citropin: Synthesis,
           characterization and in vitro efficiency study
    • Abstract: Publication date: October 2014
      Source:Reactive and Functional Polymers, Volume 83
      Author(s): Marcin Sobczak , Wojciech Kamysz , Wiktor Tyszkiewicz , Cezary Dębek , Ryszard Kozłowski , Ewa Olędzka , Urszula Piotrowska , Grzegorz Nałęcz-Jawecki , Andrzej Plichta , Daria Grzywacz , Elwira Furtak
      The effective synthesis of citropin–polymer conjugates was described in this paper. The obtained biodegradable polymeric matrices and polymeric conjugates were characterized using 1H or 13C NMR and Fourier transform infrared spectroscopies, gel permeation chromatography and scanning electron microscopy. Toxicity of polymers was evaluated with bacterial luminescence test and two protozoan assays. The in vitro release study of citropin from the obtained conjugates was investigated. The preliminary results of antimicrobial activity of the obtained macromolecular conjugates against Bacillus anthracis, Enterococcus hirae and Staphylococcus aureus were also discussed. The peptide had a high level of antimicrobial activity during 3–5weeks of the degradation process. The development of biodegradable citropin systems should be of a great interest in the delivery systems of antimicrobial agents.


      PubDate: 2014-07-28T21:34:15Z
       
  • Synthesis of poly(2,6-dimethyl-1,4-phenylene oxide) derivatives containing
           hydroxyl and amino groups by oxidative coupling copolymerization
    • Abstract: Publication date: October 2014
      Source:Reactive and Functional Polymers, Volume 83
      Author(s): Shigeki Habaue , Shigeyuki Iwai , Hidekazu Kubo , Koya Nagura , Tomohiro Watanabe , Yasuhiro Muraki , Yasuhiro Tsutsui
      Oxidative coupling copolymerization between 2,6-dimethylphenol (DMP) and functional monomers containing hydroxyl and amino groups, 2-hydroxymethyl-6-methylphenol and 2-(4-methylphenylamino)methyl-6-methylphenol, was carried out with a Cu catalyst under an O2 atmosphere. The polymerization was significantly affected by the polymerization solvent used, and the copolymers were effectively obtained by polymerization in polar solvents, such as a mixed solvent system containing methanol. The obtained copolymer containing hydroxyl groups was further transformed into polymers containing ester and urethane groups, which were used as additives for the fabrication of polyurethane films. The tensile properties of the films containing the obtained copolymers were significantly improved compared to those of films prepared without an additive, as well as films containing the homo-polymer of DMP.


      PubDate: 2014-07-28T21:34:15Z
       
  • Synthesis and characterization of a main-chain donor–acceptor type
           low-bandgap polymer by post-functionalization of a poly(arylene
           ethynylene)
    • Abstract: Publication date: October 2014
      Source:Reactive and Functional Polymers, Volume 83
      Author(s): Wenyi Huang
      I report a facile synthetic route for synthesizing a main-chain donor–acceptor type polymer containing strong electron donating dialkylamino groups and strong electron accepting 1,1,4,4-tetracyanobuta-1,3-diene (TCBD) units. To accomplish this, an electron donating monomer 4,6-diethynyl-N,N,N,N-tetrahexylbenzene-1,3-diamine was successfully synthesized by converting two carbaldehyde groups in the corresponding monomer into acetylene groups using lithium trimethylsilyldiazomethane via Colvin rearrangement. This electron donating monomer was then polymerized with a carbonyl-activated diiodide monomer to afford an electron-donating π-conjugated precursor polymer with a reasonably high molecular weight, which was further reacted with TCNE via cycloaddition/retroelectrocyclization reaction under mild conditions to afford the target polymer with a low bandgap energy ( E g opt = 1.40 eV and E g CV = 1.10 eV ) arising from strong intramolecular charge-transfer interactions between electron donors and acceptors in the polymer.


      PubDate: 2014-07-28T21:34:15Z
       
  • Use of poly(3-methylthio)thiophene blends for direct laser tracing and
           bulk heterojunction solar cells
    • Abstract: Publication date: October 2014
      Source:Reactive and Functional Polymers, Volume 83
      Author(s): Massimiliano Lanzi , Luisa Paganin , Filippo Pierini , Francesco Errani , Francesco Paolo Di-Nicola
      In this article we demonstrate the use of a blend made of two regioregular polythiophenic derivatives, namely poly(3-methylthio)thiophene and poly(3-hexyl)thiophene, to obtain conductive traces by the simple laser exposure of their thin films to a suitable laser source. The polymeric blend was also tested as a photoactive layer for BHJ solar cells, showing an improved surface morphology and a wider absorption spectrum, thus resulting in an enhanced photovoltaic performance. In the standard condition normally used for the cell preparation, we obtained a 3.16% power conversion efficiency. The device showed good reproducibility and stability over time.


      PubDate: 2014-07-28T21:34:15Z
       
  • Evaluation of hybrid polymer containing iron oxides as As(III) and As(V)
           sorbent for drinking water purification
    • Abstract: Publication date: October 2014
      Source:Reactive and Functional Polymers, Volume 83
      Author(s): Daniel Ociński , Irena Jacukowicz-Sobala , Jerzy Raczyk , Elżbieta Kociołek-Balawejder
      The objective of this paper was to evaluate the possibility of utilization of a novel hybrid polymer containing iron oxides as an arsenate and arsenite sorbent in water treatment. This material was primarily obtained as a by-product in the water de-ironing process by means of N-chlorosulfonamide polymers. The sorption properties of the hybrid polymer, including pH and coexisting ions’ influence on arsenic removal efficiency, were examined using kinetic and equilibrium experiments in a batch regime. In the column process, conducted with As-spiked natural water containing both As(III) and As(V), the breakthrough of the sorbent bed occurred after the solution amounting to about 4800 bed volumes passed through the column. The regeneration and re-use of the sorbent with NaOH and NaCl solution was also studied, indicating the possibility of repeated use of the sorbent with only a slight decrease in its sorptive properties for four cycles.


      PubDate: 2014-07-28T21:34:15Z
       
  • Enzyme immobilization on smart polymers: Catalysis on demand
    • Abstract: Publication date: October 2014
      Source:Reactive and Functional Polymers, Volume 83
      Author(s): Giuseppe Cirillo , Fiore Pasquale Nicoletta , Manuela Curcio , Umile Gianfranco Spizzirri , Nevio Picci , Francesca Iemma
      A new approach for the synthesis of hydrogel films with thermo-sensitive enzymatic activity is reported. Pepsin (PEP) was covalently immobilized on thermo-responsive hydrogels by radical polymerization in the presence of N-isopropylacrylamide and poly-(ethylene glycol) dimethacrylate 750, acting as functional monomer and crosslinking agent, respectively. Hydrogels showing lower critical solution temperatures between 32.9 and 36.1°C were synthesized by UV-irradiation of reaction batches differing in the PEP/monomers ratio. The derivatization degree of the hydrogels was expressed as mg of PEP per gram of matrix and found to be in the range of 6 to 11% as assessed by Lowry method. Scanning electron microscopy analysis and water affinity evaluation allowed to highlight the porous morphology and thermo-responsivity of hydrogels as a function of temperature. Using bovine serum albumin as a substrate, kinetics parameters were determined by Lineweaver–Burk plots and the catalyst efficiency evaluated. The influence of temperature on enzyme activity, as well as the thermal stability and reusability of devices, were also investigated.


      PubDate: 2014-07-28T21:34:15Z
       
  • Preparation and characterization of p-tert-butyl thiacalix[4]arene
           imbedded flexible polyurethane foam: An efficient novel cationic dye
           adsorbent
    • Abstract: Publication date: October 2014
      Source:Reactive and Functional Polymers, Volume 83
      Author(s): Abbas Mohammadi , Moslem Mansour Lakouraj , Mehdi Barikani
      In this study, a new type of flexible polyurethane foam containing p-tert-butyl thiacalix[4]arene (TC4A) macrocycle was synthesized. TC4A macrocycle was incorporated into polyurethane foam as a part of crosslinking agent as well as glycerol. Structural, morphological, thermal and mechanical properties of this prepared foam were studied and compared with a polyurethane foam based on only glycerol as crosslinking agent, by Fourier transform infrared (FTIR), Scanning electron microscopy (SEM), Thermal gravimetric analysis (TGA), and dynamic mechanical thermal analysis (DMTA). The effect of introduction of TC4A crosslinker on cream time, rise time, apparent density, and water absorbency of the PU foams was evaluated. Moreover, it was shown that new TC4A-based polyurethane foam (TC-PUF) can be a high performance adsorbent for removal of malachite green from aqueous media using batch adsorption technique. The adsorption results indicated that TC-PUF has a high adsorption capacity of 58.82mg/g for malachite green due to the presence of TC4A macrocycles in the structure of polyurethane foam. The kinetics of adsorption of malachite green was also investigated using the pseudo-first-order and pseudo-second-order kinetic models. The results of kinetic studies showed that the adsorption of malachite green onto TC-PUF followed pseudo-second-order kinetic model.


      PubDate: 2014-07-28T21:34:15Z
       
  • Preparation of novel antimicrobial polymer colloids based on (+)-usnic
           acid and poly(vinylbenzyl chloride)
    • Abstract: Publication date: October 2014
      Source:Reactive and Functional Polymers, Volume 83
      Author(s): R. Bengü Karabacak , Turgay Tay , Merih Kıvanç
      A novel antimicrobial colloidal system based on (+)-usnic acid, an important natural antimicrobial molecule, and poly(vinylbenzyl chloride) (PVBC) colloids was synthesized. The chloromethyl functionality on poly(vinylbenzyl chloride) was utilized to bind (+)-usnic acid. To achieve this, the resultant polymer colloids were treated with (+)-usnic acid in triethylamine. The (+)-usnic acid bound particles (PVBC/Us and PVBC/Us/Us) had positive zeta potential values in the range of pH 3–12. The antimicrobial activity of the (+)-usnic acid loaded colloidal particles (PVBC/Us and PVBC/Us/Us) was tested against various microorganisms such as Listeria monocytogenes, Staphylococcus aureus, Enterococcus faecalis, Escherichia coli, Pseudomonas aeruginosa, Salmonella typhimurium, and Klebsiella pneumonia, Candida albicans and Candida glabrata. P. aeruginosa and E. coli appeared to be the most sensitive microorganism compared to the others. The minimum inhibitory concentration (MIC) was determined using different colloid concentrations. The resultant (+)-usnic acid loaded colloids showed high antimicrobial activity against many microorganisms with MIC values down to 0.12mgcolloid/mL. While PVBC/Us/Us colloids had bacteriostatic effect against all the tested microorganisms, PVBC/Us colloids had against only four of them. Furthermore, PVBC/Us/Us colloids showed bactericidal effect against P. aeruginosa and E. coli with minimum bactericidal concentration (MBC) values of 0.94 and 3.75mg colloid/mL, respectively. In contrast, (+)-usnic acid had no activity on its own. Owing to the small and uniform sizes and high surface areas, (+)-usnic acid loaded colloids afforded greater contact area with the bacterial cell.


      PubDate: 2014-07-28T21:34:15Z
       
  • Effect of photofunctional organo anion-intercalated layered double
           hydroxide nanoparticles on poly(ethylene terephthalate) nonisothermal
           crystallization kinetics
    • Abstract: Publication date: October 2014
      Source:Reactive and Functional Polymers, Volume 83
      Author(s): Tianchi Cao , Yang Feng , Guangming Chen , Cun-Yue Guo
      Very recently, we report a facile preparation and strong UV-shielding function of poly(ethylene terephthalate) (PET) nanocomposites using 4,4′-diaminostilbene-2,2′-disulfonic acid anion-intercalated layered double hydroxide (LDH_DDA). Herein, the effect of the photofunctional organo anion-intercalated LDH nanoparticles on nonisothermal crystallization kinetics of PET is reported by differential scanning calorimetry technique. First, the nonisothermal crystallization behaviour is discussed by several basic parameters including crystallization peak temperature, relative degree of crystallinity with temperature or time, and half-time of crystallization. Then, Avrami and Jeziorny method, as well as Mo model were applied for the PET/LDH_DDA nanocomposites. Finally, the crystallization activation energy was investigated by Kissinger method and Flynn conversion. The results reveal that the incorporation of LDH_DDA nanoparticles acted as nucleating agent and significantly accelerated the PET nonisothermal crystallization process, whereas had little effect on the three-dimensional growth pattern of spherulites.


      PubDate: 2014-07-28T21:34:15Z
       
 
 
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